Squeegee device

ABSTRACT

A squeegee device for stencil printing machines having rotary screens wherein the squeegee is arranged on the squeegee carrier movable towards the support. The squeegee is under the action of forces directed to the support and essentially distributed over the working breadth. The squeegee on the one hand and one element of the support on the other are working elements acting on each other by magnetic forces wherein at least one of the elements is magnetic and the other at least partially of magnetizable material. An ink pipe projects inside a rotary screen and the squeegee carrier is connected with the ink pipe. A slit open towards the support is provided in the squeegee carrier and the squeegee is adjustable in the slit.

United States Patent Primary Examiner-Robert E. Pulfrey AssistantExaminer-Alan E. Koepecki AttrneyWenderoth, Lind and Ponack ABSTRACT: Asqueegee device for stencil printing machines having rotary screenswherein the squeegee is arranged on the squeegee carrier movable towardsthe support. The squeegee is under the action of forces directed to thesupport and essentially distributed over the working breadth. Thesqueegee on the one hand and one element of the support on the other areworking elements acting on each other by magnetic forces wherein atleast one of the elements is magnetic and the other at least partiallyof magnetizable material. An ink pipe projects inside a rotary screenand the squeegee carrier is connected with the ink pipe. A slit opentowards the support is provided in the squeegee carrier and the squeegeeis adjustable in the slit.

[72] Inventor MathiasMitter Klagenfurt, Austria [21] AppLNo. 731,549[22] Filed May 23,1968 [45] Patented Mar. 2, 1971 [73] Assignee JohannesZimmer v Klagenfurt, Austria [32] Priority May 26,1967 [33] Austria [31]A4888/67 and A7591/67 [54] SQUEEGEE DEVICE 2 Claims, 1 Drawing Fig.

U.S.Cl 101/120 841113/06 FieldofSearch 101/123,124,119,l20;118/(D&S);15/256.5l

[5 6] References Cited UNITED STATES PATENTS 764,275 7/1904 Dick101/120X 1,264,506 4/1918 Hahn (118/D&S) 1,312,034 8/1919 Jones(ll8/D&S) 1,993,055 3/1935 Gerstenberg..... (ll8/D&S) 2,330,889 10/1943Holcomb l5/256.51 2,695,004 11/1954 Montgomeryetal (ll8/D&S) 2,920,557l/1960 Fuchs (ll8/D&S)

MATHIAS MITTER,

INVENTOR.

BYLOWMZJ;

stencil printing machines comprising rotary screens.

Squeegee devices particularly serve for regularly applying and/ordistributing liquid, in particularviscous or pasty masses.

on surfaces which are only curved in one dimension,

preferably on material blankets or cylinders. However, 1

on the surface to be treated and another case inwhich the squeegee ispressed against a permeable screen, e.g. in screen printing, which restson the surfaces to be coated or printed, e.g. on the material. a a

As to construction, there are two basic types of squeegees; the slidingsqueegee on the one hand and the roller squeegee on the other; thelatter. rolls off in relation to the surface to be treated or to theprinting screen, .thusapplying the massif the case may be through theperforations of a printing screenon the surfaceto be treated. 1 I

In principle, the simplest solution lies in a roller squeegee which ismagnetically attracted by a magnet body under the blanket; in this caseonly a cylindrical bar of magnetizable material is required which neednot'be stored. It has been proved in practice, however, that, eg instencil printing machines comprising rotary screens under specifiedworking conditions, in the case of high printing speeds and upon theutilization of a printing ink of" high tenacity, the roller squeegee isshifted into the direction of movement of the screen wall or isdeflected fro'mits position parallel to the screen axis or is evenslightly bent. Thus the gap betweenthe roller squeegee and the magnetbody under the blanket or material to be printed is increased while themagnetic attraction diminishes. Besides, the ink supply lying in frontof the roller squeegee is augmented. As 'a result,'the printing qualityis constantly had or. irregular. Similar phenomena are observed in otherapplications of rollersqueegees. These disadvantages are avoided in thesliding squeegee which is stationarily fixable but in the known devicescomprising such sliding squeegees the mounting and adjustment of thesliding squeegee .require. considerable expenditure. Further,- more, itis very difficult to press the squeegee against the support by regularpressure over the whole working breadth.

erted do not act on the carrier, but directly on the squeegee.

In the device according to the invent on, the worklng edge of thesqueegee automatically adjusts to the support and automatically followspossible variations of movement or thickness of the support withoutlosing contact therewith and without exerting a strong braking effect onthe parts movable in relation to each other. If the squeegee is abladeresistant to bending, the angle chosen between the blade-and the supportis maintained, the thickness of the mass-applied depending on saidangle. By arbitrarily rotating the squeegee carrier, said angle and thethickness of the mass applied can be arbitrarily modified, the squeegeeblade automatically adjusting to the support upon each rotation of thecarrier.

To movably arrange the squeegee on the carrier, it is convenient toprovide a slit open towards the support in the carrier, the squeegeebeing adjustable in said slit.

The required force acting on the squeegee can be obtained withthe'squeegee.

Another convenient. solution consists in that the squeegee on the onehand and one element .of the support on the other are working elementsacting on each other by magnetic forces,

In the FIG. 1 a device for a stencil printing machine com- I prisingrotary screens is shown. The ink pipe 19 through which desired means.

It is .commonly. known that a squeegee blade rigidly mounted on acarrier resistant to bending, the squeegee bar,

presses more strongly against the support in the marginal zones than inthe medium zone if the forces by which the squeegee is generally pressedagainst'the' support, act on the extremities of the squeegee bar. a 7

Therefore squeegee blades havi'n'g curved working edges are generallyused which become linear by the action of the exerted forces acting onthe extremities of the squeegee bar. However, it is very difficult toproduce squeegee blades having an appropriatelycurved working edge,e-.g. by sharpening or curving by means of a system of puller screws.

It is an object of the invention to create a device comprising a slidingsqueegee having a simple construction which is easily adjustable andguarantees a pressure as regular as possible of the squeegee blade onthe support, irrespective of possible deflections of the squeegeecarrier.

According to the invention this is obtained in that the squeegee ismovable on the carrier toward the support and that the squeegee itselfis under the action of forces directed to the support, regularlydistributed over the working breadth. It is obtained according to theinvention that the working edge of the squeegee, preferably shaped likea blade, exerts a regular pressure on the support over the whole workingbreadth, irrespective of possible deflections of the squeegee carrier,because, according to the invention, the forces ex- The support overwhich the material 13 to be printed is led by means of a blanket 12, isa magnet bar 23 which attracts the squeegee blade 4; thus the workingedge of the blade is pressed against the screen inwall. A magnet rollercan also be applied as a support instead of a magnet bar.

A device for controlling the level of the printing ink is joined tothesqueegee carrier 21 whose electric tracer 24 is connected with theelectric control of the ink supply through a cable 25.

As can be seen in the FIG. 1, the working element of the squeegee neednot necessarily have the form of a flat sheet, but it can also be aprismatic body and even a round bar which is adjustable on the squeegeecarrier movably towards the support.

lclaim:

l. A squeegee device for a stencil printing machine comprising a rotaryscreen mounted in said machine, a support for the material to be printedcooperatingwith said screen, a squeegee carrier located within saidscreen, a squeegee slidably mounted in said carrier and movable towardssaid support, said squeegee being under the action of forces directedtowards said support and essentially distributed over

1. A squeegee device for a stencil printing machine comprising a rotaryscreen mounted in said machine, a support for the material to be printedcooperating with said screen, a squeegee carrier located within saidscreen, a squeegee slidably mounted in said carrier and movable towardssaid support, said squeegee being under the action of forces directedtowards said support and essentially distributed over the workingbreadth of said squeegee, an element of said squeegee and an element ofsaid support coacting on each other by magnetic forces, one of saidelements being magnetic and the other at least partially of magnetizablematerial, an ink pipe projecting inside said rotary screen and saidcarrier being connected to said ink pipe.
 2. A squeegee device accordingto claim 1 wherein said squeegee carrier has a slit open towards saidsupport and said squeegee is mounted in said slit.